Electronic device



Nov. 18, 1947. J. E. WHITE ELECTRONIC DEVICE Filed May 16, 1945 2 Sheets-Sheet 1 Z Il 1 4J ZH INVENTOR JTE'. [VH/TE ATTORNEY NOV. 18, 1947. J, E, wHn-E 2,431,153

ELECTRONIC DEVICE Filed May 16, 1945 2 Sheets-Sheet 2 CAD/021i INVENTOR JE'. 4v/ft' ATTORNEY Patented Nov. 18, 1947? UNITED STATES PATENT OFFICE ELECTRONIC DEVICE John E. White, Bloomfield, N. J., assigner to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application May' 1s, 1945, serial No. 594,016

s claims. (ci. o-27.5)

This invention relates to electronic devices and more particularly to heat transfer means associated with one or more of the electrodes thereof.

One 'cf the diiiiculties encountered in operation of electronic tubes is the variation of temperature during operation. In most instances, the temperatureinmcreases during operation, and to simplify description, particular reference will be made to heat exchange by which the electrode involved is to be cooled, but it is to be understood the invention is not thereby confined solely to that use. Furthermore, for purposes of illustration, a pool type electronic device has been selected lor exemplifying the invention, but again, itis to be understood the concept is applicable to other electronic devices, such as thyratrons, as`

well as to heat exchange in general where automatic control of passage of heat by conduction is desired. Broadly stated, an object of the present invention is to provide improved heat exchange control between thermally conductive elements.

Also in its broad aspects, an object of the` invention is to provide automatic regulation ot the heat exchange. c"

More specifically, an object of the invention is to provide an automatic heat control for electrodes f.

of electronic devices.

A further object of the invention isvto permit the electrode with which the invention is asso-f l,

ciated to quickly mount to substantially the vdesired operating temperature.

Another object is to maintain the temperature', after reaching the substantially desired tempera-` ture, at a substantially constant level over a relatively wide operating range.

Yet another object of the invention is to' provide for substantially no heat transfer' under starting conditions and to provide for very large heat transfer under operating conditions which are productive of excessive heat on the electrode.

Figure 3 is a cross sectional view on line III-III section II o1' borosilicate glass with two metallic end cups I2, I3 sealed thereto. Preferably the said cups may Well be a' nickel-cobalt-iron alloy described in Patent 2,062,335 of Howard Scott, dated December 1, 19,36, that alloy being sold under the trade name of Kovar."

Cup" I2'toward the bottom end of the device functions asa container for a cathode pool I4 and shown at the middle of the bottom or end wall I5 of said cup is a depression' I6 for obtaining adequate depth thereatof the pool for immersionv of the tip of a starter electrode or ignitor I'I. Said ignitor is suspended within the envelope by a suitable transverse lead-in connection I8 extending through one side of saidv cup with a vacuum tight insulative seal I9 between the ignltor and lower cup. The upper cup I3 functions asthe anode and is shown with a hat end wall 20.

'At the exterior of each said cup I2 and I3 Still other objects of the invention will appear to those skilled in the art to which the invention appertains as the description progressesboth by direct recitation therein and by inference from the context.

Referring to the accompanying drawing in which like numerals of reference indicate similar parts throughout the several views; f

Figure 1 is a longitudinal section of an ignitron, representative of an electronic device, embodying the present invention;

Figure 2 is a detail cross section on line II-l-IIv of Fig. 1, and showing clip mounting for the device; f y

I5 and 20 thereof, as by welding, brazing, soldering or other suitable means, is a heat conductive and preferably metallic body 2 I. Each said body is shown as having a diameter substantially the same as the cup to which it is secured, and is shown solid to provide a mass considerably greater than the cup, and furthermore shown of greater length than the cup and as having a convex or rounded outer end. 'I'he basal end of each said body 2|, that is, the end next to and xed on the end .wall of the cup is preferably slightly greater in diameter than the majority of the length of said body to provide a projecting or peripheral rim to which is attached one end of a collar 22.

' Said collar is coaxial with said body and of greatlili er length than said body so as to project beyond the-said rounded end of the body. Except for the end margin of the collar which attaches to the end rim of the body, said collar is spaced from the body leaving a peripheral air gap 23 between ycollar and body for most of the length of said body. Secured by the outer end of each collar which projectsv beyond the body, is a radiator core 2l, theend of said core toward the body being concave in parallelism to the convex contour of the end 01' the body 2l. Beyond the collar, said atmosphere transmitted by conduction from the core to the iins. At normal temperature, the convex and concave surfaces of body and core are spaced apart with a gap 2S of predetermined dimension. For establishing that gap, it is preferable to thread the contiguous cylindrical faces of the collar and core, as at 2l. and provide a set screw 28 laterally through one wall of the collar to engage the core for locking those parts in adjusted relation.

If so desired, the envelope I0, heat conductive bodies 2| and collars 22 may be included coaxially within an enclosing insulative tube 28 spaced radially outward by means of end rings 30 lling the gap between the end margins of the said tube and the end margins of the collars. These rings 30 may be of metal and soldered or otherwise secured to the collars. Aorementioned set screws 28 extendthrough the tube wall and collars and thereby also retain the tube from longitudinal displacement. On the outside of said tube, in the vicinity of the end walls f cups I2, I3 are metallic contact rings 3| in electrical connection, as by wires 32, with the said cups or their associated bodies 2|. The device may then 'both be supported and given circuit connection to the anode and cathodethereof by spring clip xture members 33 shown in Figure 2. The construction above described yconstitutes a plug-type temperature regulator having utility in connection with many devices -involving the problem of heat exchange, of which the ignitron shown is the selected example for this disclosure. Heat is generated in operation of the device of the present exemplication from arc discharge and ionic and electronic bombardment. By conduction, that heat raises the temperature of bodies 2|. Those bodies are preferably of a material, such as copper orv aluminum, having a larger coefficient of expansion than the material comprising collars 22, which may be the aforementioned alloy, namely Kovar or other alloy or metal having a lower coenlcient of thermal expansion than said bodies. As a generality, heat developed will expand the body 2| more than the collar and at some predetermined temperature the gap 26 between the body and core closes, thereby permitting a larger ow of heat, by virtue of conductionto the core and dissipation of the heat by means of the radiator ns. In greater detail, the action closing the gap is gradual as the temperature rises and at the first instant of closure of the gap a cold wave will start back along the body from the contacted cooler core which breaks the contact due to resultant contraction. The cold wave reaching the electrode cup lowers its temperature temporarily, but continued generation of heat therein again transmits through the body and the closing action of the gap repeats. Thus a series of contact making and breaking occurs with slight iiuctuations ofthe temperature of the electrode until the heat input becomes great enough to maintain the gap continuously closed.

By utilizing a body of greater lengtha gap of given dimension will be closed quicker than a gap of the same dimension but at the end of a shorter body. This fact is made use of in the present showing by utilizing a body 2| next the cathode which is longer than the body 2| next the anode, and thus, with the gaps 26 normally the same dimension, the one from the cathode will close with the anode, and thereby maintain the cathode at a lower operating temperature than the anode. There is, therefore, a very considerable period during `which the temperature will be maintained substantially constant for the electrode, diierent for each electrode, and this period is indicated in the graph of Figure 3 between critical points 34 and 34 of gap initial closing and of maintained closing at 35, 35 respectively for the cathode and anode. Without attempting to show the slight fluctuations above mentioned, the graph shows, by the horizontal line between the points rmentioned a substantially constant temperature following upon the quick rise to that temperature. Enclosing the heatexchange elements, namely, the bodies 2| and cores 24 within, the tube 29 which is heat insulative, as well as electrically insulative, for the specific exemplification, not only augments quick rise of temperature, but better assures the maintenance of the substantially constant temperature levels indicated by the graph.

It will be appreciated that in ignitrons, of which an example is specifically shown, or in other electronic devices of similar nature, such as thyratrons, a gaseous medium for ionization is employed. Mercury vapor in the envelope, evolved from a mercury pool cathode is a common expedient. The invention is not limited to a mercury pool, and is indeed, intended more particularly for use with potassium, sodium, cadmium, tin or other pools which at room-temperature are not fluid but are of a solid nature, and have tool low a vapor pressure to operate a gas iilled electronic device but which may be used at higher temperatures than mercuryand are more susceptible to the control of temperature by air cooling as above described, By use of the structure above described and. for instance, a potasf ture.

slum pool, the radiators obtain temperature variation dependent upon the load, but keep the pressure-fixing internal temperature nearly constant over a wide range of loads.' As a concrete example 'of an electronic device, an ignitron with a potassium pool or cathode may carry 60 amperes average at 30 C. ambient tempera- The potassium will supply a vapor pressure of one micron, favorable for ignitron operation, at approximately C. As another example, cadmium will supply one micron pressure at 210 C. and the radiator fins would therefore be somewhat smaller than the device employing a potassium cathode.

In operating the device, power applied to the igntor will quickly melt the cathode pool (melting point of potassium being 62.3 C.). At all loads, the cathode is the coolest part of the internal region of the device, so that the potassium evaporates from and recondenses on the cathode without contaminating the anode and causing arcbacks.

By reference to Figure 3 showing temperatures as functions of load, it will be seen that from about two amperes load at points 34 and 3d where the initial closure of gap 2B for the anode and for the cathode occur, up to about 50 amperes at points 35, 35' where the gap is maintained closed, the cathode temperature remains at 170 C., and the anode remainsat about 300 C., and the vapor pressure remains at one micron. Be-

yond 50 amperes, the cathode temperature begins at a lower temperature than the one associated '(5 a quite favorable operating pressure, corresponding to pressure at about 40 C. for a mercuryvapor device. It may be further mentioned that the device can be adjusted to operate at other critical or constant temperatures than those shown on the graph.

Adjustment for desired temperature constant is first made by screwingr the radiator cores into contact with the heat-exchange bodies, and then unscrewing by the amount necessary to give the desired temperature in operation. To give theV temperatures shown on the graph in the device as illustrated, a gap of .0026 inch was found acceptable. In practice this gap is obtained by using sixty threads per inch on the radiator core and the sleeve, and backing the radiator core away from body contact by unscrewing fty seven angular degrees. Use of aforementioned Kovar to comprise the sleeve and copper to constitute the heat exchange body obtain the results shown by the graph. It may also be emphasized that the invention makes use of an alkali metal, such as potassium or sodium as the cathode pool instead of mercury, is not only practical but highly advantageous, and obtains increased power output and a reduced arc drop over use of a mercury pool.

I claim:

1. An electronic device inherently productive of heat, means external to the device constituting a heat transmitting body for heat produced in said device, heat radiating means proximate to said body, said body also constituting a proximityvarying means maintaing a gap between the body and radiating means up to a predetermined temperature and automatically closing` said gap by heat expansion of said body and thereby promoting conduction of heat from said body to said radiating means above a predetermined temperature.

2. An electronic device having an electrode subject to increase of temperature in use, means external to said electrode and device in lheat-conductive contact with said device for transmitting heat therefrom, and heat radiating means normally spaced from said heat transmitting means and contactable therewith as the result of heat expansion of said heat transmitting means.

3. An electronic device having an enclosed envelope and electrodes of which one is subject to increase of temperature in use, a body external to the envelope and integral with said electrode subject to increase of temperature, said body being heat conductive and expandable due to heat, and a radiator having a core in proximity to said body and normally providing a gap between said core and body, said core being' relatively fixed and the gap adapted to be closed by expansion of the body due to heat increase in the body whereby the core receives heat from the said body by conduction at and above a predetermined temperature of the said electrode subject to increase of temperature.

4. An electronic device having an electrode subject to increase of temperature, a body in constant and extensive contact withsaid electrode for transmitting by conduction heat from said electrode, said body being heat-expandable in a direction perpendicular to said extensive contact of the electrode and body, a radiator core opposed to the said body in the path of expansion of the said body, and means supporting said core substantially xed with respect to the said electrode and with a gap normally between said core and body whereby expansion of the body obtains contact thereof with said core.

' 5. Anelectronic device comprising an envelo having headers at opposite ends thereof, a heat conductive body on each said header projectingnormally therebetween. said body being expandable from heat of conduction from the header an amount equal to the normal gap distance between said body and core for closing the gap and enabling heat of the body to be transmitted by conduction to said core and radiator.

6. An electronic device comprising an envelope having headers at opposite ends thereof, a heat conductive body on each said header projecting outwardly therefrom, a radiator for each said body, said radiator having a core as a substantial continuation of the said body in the same outwardly projecting direction of the projection of said body from the respective header, and means holding said core and body with a gap normally therebetween, said body being expandable from heat of conduction from the header an amount equal to the normal gap distance between said body and core for closing the gap and enabling heat of the body to be transmitted by conduction to said core and radiator.

7. An electronic device comprising an envelope tial continuation of the said body in the same i outwardly projecting direction of the projection of said body from the respective header, and a collar coaxial to each said body and core secured thereto at opposite ends of the collar and holding said core and body with a gap normally therebetween, said body being expandable from heat of conduction from the header an amount equal tothe normal'gap distance between said body and core for closing the gap and enabling heat of the body to be transmitted by conduction to said core and radiator.

8. An ignitron having an anode and pool cathode of low vapor pressure material. as a vapor source, said cathode requiring a considerable use of temperature above room temperature for attaining normal operating temperature and said anode being heated by discharge between the cathode and anode, radiators for both the anode and cathode, and two heat-operated means interposed one between the anode and its radiator and another between the cathode and its radiator, the two said heat-operated means being constructed and arranged to automatically connect the anode and cathode with their respective radiators at different temperatures of the cathode and anode.

9. A temperature regulator of the character described comprising in combination with a source of heat, a iirst element receptive of heat from said source and conductive thereof and expandable due thereto, and a second element normally spaced by a gap from said rst element and contactable over an extensive surface area by the rst element upon expansion of the first element aonucad away fram th ontacting surfaces o said elemems.

JSE? Wim.

The following references are 01 recorz :ln the fue of this patent:

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